Send the reorder email before they run out.

When you set up the replenishment flow, you set the reminder to the supply length. A 30-day bottle, a day-30 email. That's the decision most owners make, and it's the honest one: don't nag people who still have product. It also misses the moment that matters. The reorder isn't won on the day they run out. It's won in the week before, while the bottle is low and the thing they bought it for still feels like it's working.

Empty is too late

Look at day 30 from the customer's side. The bottle ran dry on day 28. Two mornings have gone by without it. Whatever it was doing has started to fade, and so has the routine it lived in, because a routine with a missing piece stops being automatic. Now your email arrives: time to reorder. It reads as a task. They mean to get to it, and then it's day 40.

Day 22 looks different. The bottle is visibly low. They're still using it every morning, still feeling it, and the feeling is the thing they'd pay to keep. An email on that day isn't a reminder about a chore. It's permission not to lose something. The early win is when people say yes to more of it, not after weeks of silence, and on a consumable the early win has a shelf life measured in days.

My working rule, and the one every reorder curve I've looked at points to: on a 30-day supply, remind around day 20 to 25. Scale it to pack size, so a three-bottle bundle gets its reminder around day 75, not day 90. The principle holds at any size. The message lands while they're still in the part where it works.

When to send a replenishment email: your customers already told you

Day 20 to 25 is where I start. It isn't where I finish, because the label says 30 days and your customers don't read labels. Some double up. Some skip weekends. Some bought two and are on the second bottle. The real reorder day is sitting in your order history, and pulling it takes an afternoon.

Export every customer with two or more orders. For each one, count the days between order one and order two. Then chart how many second orders fall on each day. You'll see a hill, with a peak where your natural reorder day actually lives, and a long tail where the people who waited too long trickle back. Set the reminder to land where the hill starts to rise, just before the peak. That's the day the customer was already thinking about it, and your email arrives looking like it read their mind. A spreadsheet and a pivot table will build the chart; so will handing the export to an AI and asking for the day-by-day count. The analysis is the easy part. Having the export is what most owners skip.

The same chart answers two more questions. Where the hill flattens into the tail is where a customer has quietly lapsed, and that's where the reminder stops and a win-back starts, a different email with a different job. And if you sell more than one consumable, chart each one separately, because a 60-serving tub and a 30-day bottle have different hills, and one reminder day for both is wrong for both.

What the email says when they're not empty yet

Once the reminder moves to the rise of the hill, the copy has to move with it, because almost every replenishment email I read was written for day 30. A reminder written for day 30 says you're out, reorder. A reminder written for day 22 can say something better: you're three weeks in, this is the part where it's working, keep it going. It assumes they're still using it, because they are, and it talks about the next 30 days instead of the last.

Four emails, spaced across the window. First, running low: a plain note that the bottle's getting light and the reorder is one click away. Second, a founder check-in: three weeks in, how's it going, hit reply. Third, the long game: what consistency looks like at week six and week twelve, because the result builds with time and the long-term benefit is the real reason to keep going. Fourth, the subscription, and this is the right day for it. "Never run out" means nothing to someone holding a full bottle and everything to someone who just felt the first one go light. You're taking it anyway. Subscribe and stop thinking about day 22.

It's also the window for the next offer, if you have one, and the founder check-in is how you find who's ready for it. A reply three weeks in saying it's working is the honeymoon, and the honeymoon is when "if this worked, imagine that" lands. Send that offer to the people who replied, not to the whole cohort on day 22. Wait for the empty bottle and you're pitching to someone who's started wondering whether it worked at all.

A reminder only works on someone who used the bottle

Everything above assumes the bottle is low on day 22, and the four emails are written to someone mid-routine. For a share of your customers the bottle isn't low, because they used it four times and put it in a drawer, and to them those four emails read as noise, because no reminder on any day gets a reorder out of a full bottle. The replenishment flow sits on top of the consumption flow, the education in the first ten days that gets the product used at all, which I lay out in why customers don't reorder. Build them in that order. A perfectly timed reminder to someone who never started is a perfectly timed email about nothing.

Then two mechanical checks. The trigger: a replenishment flow has to fire off the placed order for that specific consumable, with the delay set to your curve and not the platform's default, or the day you just found never reaches anyone. And the send-through. Live is not the same as sending, and a replenishment flow that skips most of the people who enter it looks healthy from the revenue screen; I covered the ten-minute way to tell the two apart in why email revenue drops, and it applies to this flow as much as to the welcome flow. Replenishment is one flow in the post-purchase system, and how it sits next to the review ask and the cross-sell is in the post-purchase flow.

Charting the reorder curve and rebuilding the replenishment flow around it is a standard first-week job on my retention accounts, because it's a data pull before it's a copy job, and most owners have never seen their own hill. If you sell something people run out of, the email & SMS service starts there.

Common questions

When should I send a replenishment email for a 30-day product?

Around day 20 to 25, while the bottle is low and the product still feels like it's working, not on day 30 when it's empty. Scale to pack size: a three-pack gets its reminder around day 75. Then adjust to your own reorder data, which usually moves the day.

How do I find my real reorder timing?

Export customers with two or more orders, count the days between their first and second order, and chart how many second orders land on each day. The peak is your natural reorder day. Set the reminder to land just before it, and chart each consumable separately.

Should the replenishment email include a discount?

It doesn't need one, and leading with one trains people to wait for it. The reason to reorder is the result they're feeling, so the email talks about keeping that going. Hold offers for the back end of a win-back, after the reorder window has clearly passed.